The dynastic Dallas Cowboys of the early to mid-1990s were powered by The Triplets: quarterback Troy Aikman, running back Emmitt Smith and wide receiver Michael Irvin.

The 2019 49ers don’t necessarily have three future Hall of Famers, but they are developing a similar ability to shred defenses in different ways.

That’s according to a knowledgeable source: former Cowboys fullback Daryl Johnston, a Pro Bowl member of those Dallas teams that won three Super Bowls in four seasons. Johnston, a Fox TV analyst, is preparing to call the 49ers’ game against the Falcons on Sunday at Levi’s Stadium.

One of Johnston’s takeaways after studying Sunday’s 48-46 win in New Orleans and calling two other 49ers games this season: Their offensive versatility evokes fond memories.

“There are a lot of teams that want to come out and shut that run game down, and that leaves you vulnerable in the passing game,” Johnston said. “And that’s how we functioned in Dallas. If you’re going to make it your primary goal to stop Emmitt Smith, you’re going to have to deal with Michael Irvin, (tight end) Jay Novacek and (wide receiver) Alvin Harper in the passing game.

“The great thing is when you get your offense to a point where both facets are so dangerous. And I think that definitely is the track the 49ers are trending toward right now.”

Much of the credit for the 49ers’ 11-2 start has gone to their pressure-happy, second-ranked defense, which ranks third in the NFL in sacks.

And the gradual emergence of their offense has been largely overshadowed — at least until Sunday’s 516-yard explosion in New Orleans.

The 49ers own the league’s second-ranked rushing game. And their passing game has been catching up with their ground attack since their October trade for a legitimate top-end wide receiver, Emmanuel Sanders, whose arrival coincided with a steep uptick in quarterback Jimmy Garoppolo’s production.

Since Week 8, Sanders’ first game, Garoppolo ranks second in the NFL in passing touchdowns (16) and third in passing yards (1,756) and passer rating (113.5).

As a result, the 49ers rank third in the NFL in points and fourth in total yards, which is notable. They are one of three teams (along with the Titans and Dolphins) that haven’t ranked among the league’s top 10 in either category since 2003.

On Sunday, Garoppolo threw for 349 yards and four touchdowns, but the 49ers also rushed for 162 yards, and their top two rushers, Raheem Mostert and Matt Breida, averaged 7.7 yards on 16 total carries.

“That offense is built around the running game,” Johnston said. “There’s a huge emphasis on it. Kyle (Shanahan) will not get away from it. Even last Sunday where everyone is raving about how well Garoppolo played, they still run for 160-plus yards. …

“That gives them the ability to look at what is favorable each week, and Kyle has the ability to attack defenses that way.”

The 49ers’ ability to zig or zag was best illustrated in their 36-26 win over Arizona in November, which was the last 49ers game Johnston worked. The Cardinals sold out to stop the run and succeeded: The 49ers had a season-low 34 rushing yards … and Garoppolo threw for a career-high 424 yards and four touchdowns.

Johnston was part of Dallas teams that went 8-24 in head coach Jimmy Johnson’s first two seasons before producing an 11-5 record and their first playoff berth in six seasons in 1991.

The 49ers went 10-22 in Shanahan’s first two years and are poised for their first playoff berth in six years this season.

Johnston, a pass-catching fullback like the 49ers’ Kyle Juszczyk, sees other similarities. And one of them involves Pro Bowl tight end George Kittle, whom Johnston is eager to see after Kittle was sidelined when the 49ers beat Arizona in November.

“Michael Irvin was the emotional heart and soul of our offense, and you can tell George Kittle is the emotional heart and soul of that offense,” Johnston said. “That’s a key component. There are a number of different similarities, and it will be interesting to see how this team continues to grow.”

Eric Branch has worked at the San Francisco Chronicle since 2011 as the 49ers beat writer. Before that, he covered the 49ers for the Santa Rosa Press Democrat in 2010. Since he began his career in journalism in 1997 in Logansport, Ind., he’s covered events ranging from archery tournaments to the NCAA Men’s Basketball Tournament.